Indian Standard CODE OF PRACTICE FOR CANAL OUTLETS ( Third Reprint AUGUST 1988) IS : 7986 - 1976 ( Reaffirmed 2004 ) VW 626.1:627.833 BUREAU MANAK OF BHAVAN, INDIAN STANDARDS MARG 9 BAHADUR SHAH ZAFAR NEW DELHI 110002 Gr 3 Muy 1976 lSt7986-1976 Indian Standard CODE OF PRACTICE FOR CANAL OUTLETS Canals and Canal Linings Sectional Committee, BDC 57 Chairman SHRI K. S. PATHAK Members SHIU M. M. ANAND SHRI S. S. Sa3xI ( Alternate) SHIZI S. P. BEAT Represmting Water and Power Development Consultancy Services ( India ) Ltd, New Delhi Irrigation & Power Department, Punjab, Chandigarh Government of CHIEB ENOINEER ( IRRIQATION ) SR~I K. SUNDRAM ( Allernate ) SXRI 0. P. DATTA SHRI R. L. DEWAN Public Works Department, Government of Mysore, Bangalore _ Public Works Denartment . Government of Tamil Nadu, Mad& ' Beas Designs Organization, Nangal Township Bihar Institute of Hydraulic & Allied Research, Khagaul DIIWDCTOR ( BD ) Central Water Commission, New Delhi DEPUTY DIRECTOR ( BD ) ( Alternate ) Irrigation Department, Government of Rajasthan, DIRECTOR Jaipur DIREOTOR Land Reclamation, Irrigation & Power Research Institute, Amritsar PHYSICIST (Alternate ) SHRI S. D. K~LKAENI Irrigation & Power Department, Government of Maharashtra, Bombay SIIRI A. A. PAi ( Alternate ) SHRI K. M. M~HEIE~EWARI Planning Commission, Government of India SHRI P. W. P~RWANI (Alternate ) SHR~ M. A. ME~TA Concrete Association of India, Bombay SHRI Y. K. MEHTA (Alternate) REPBESENTATIVE Irrigation Department, Government oi Fl:rryIIna, Chandigarh SHRI P. C. SAXENA Central Water & Power Research Station, Pune SHRI V. P. BHATT ( Alternate j SECRETARY Central Board of Irrigation & Power, New Delhi SHBI H. D. SI~A~MA Irrigation Research Institute, Roorkee (Continued on page 2 ) @ Co&e& 1976 BUREAU OF INDIAN STANDARDS This publication is protected under the Indian Copyrtght Act (XIV of 1957) and reproduction in whole or in part by any means except with written permission of the publisher -hall be deemed to be an infringement of copyright under the said Act. Members Smu Representing Water Resources & M.K. SINGEAL SUBUDHI SEEXK. T. SUPE~INTEND~NQ ENUINEE~ SESI P, s. You SEW D. A.TXTHA SINHA, Director ( Civ Engg ) Development Training Centre, University of Roorkee, Roorkee Irrigatron & Power Department, Government of Orissa, Bhubaneswar Irrigatron & Power Department, Government of Haryana, Chandigarh Irrigation & Power Department, Government of Uttar Pradesh. Lucknow Director General, BlS ( Ex-ofi& Mmber ) SERI V. KALYANABUNDABAM Assistant Director ( Civ Engg ), BIS ISt7986-l976 Indian Standard CODE OF PRACTICE FOR CANAL OUTLETS 0. FOREWORD 0.1 This Indian Standard was adopted by the Indian Standards Institution on 23 February 1976, after the draft finalizkd by the Canals and Canal Linings Sectional Committee had been approved by the Civil Engineering Division Council. 0.2 Various types of canal outlets have been evolved from time to time to obtain suitable performance No one type has come out to be suitable universally. In fact it is very difficult to achieve good design with respect to ' flexibility ' and ` sensitivity ' because of various indeterminate conditions both in distribution channels and the water course, namely, discharge levels, silt charge, capacity factor, rotation of channels, regime condition of distributing channel, etc. Variation in any of these factors affects proper working of an outlet. Even a particular type of outlet considered suitable upstream of a control structure in a channel may not remain suitable for a considerable distance on the same channel. However, the information collected on the subject indicates that pipe outlet, both of non-modular type and semi-modular type, depending upon method of installation and open flume outlets and Chump's adjustable proportional module of semi-modular type has generally been adopted in the country. This standard has been prepared to give general guidance in respect of selection and installation of these outlets on irrigation channels. 0.3 For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with The number of significant places retained in the rounded off IS : 2-1960*. value should be the same as that of the specified value in this standard. 1. SCOPE 1.1 This standard covers general classification of outlets installed on irrigation channels and. gives general guidance for selecting and installing non-modular and semi-modular outlets. l p@s for roundingoff numetica~ dues ( ravisrd ) . 3 IS : 7986 - 1976 :?. TERMINOLOGY AND NOTATIONS 2.0 For the purpose of this standard, the following definition shall apply. 2.1 Outlets - A device through which water is released from a distributing channel into a water course ( cultivators' channel ). The discharge through an outlet is usually less than 0'085 cumecs. 2.2 Notation - Unless otherwise stated, the following notations have been used in the formulae given in 5 and 6. q Discharge in cumecs of an outlet A - Cross-sectional area of pipe in cm0 H = Difference of water levels in the distributing channels and water course in metres g = Acceleration due to gravity in m/s' Bt = Width of throat of weir in an outlet in metres Hs = Head measured from F. S. L. in the distributing channel to the crest of outlet (H) minus depth of orifice 2" in m. D = Depth of water in distributing channel in m Cumecs = Cubic metres per second W = Setting forward of the d/s wing wall of the approach Q = Discharge in cumecs of a distributary channel upstream of the outlet k = Ratio between the mean velocity for the entire diributing channel and mean velocity in the part of the distributing channel, wherein outlet is to be installed. Bu = Bed width of the distributary channel upstream of the outlet. 3. CLASSIFICATION OF OUTLETS 3.1 Outlet may be classified in the following three types: a) JVon-modular Outlets - Non-modular outlets are the outlets whose discharge is a function of the difference in water levels in the distributing channel and the water course and variation in either affects the discharge. These outlets consist of rectangular or circular openings' and pavement. The effect of downstream water level is more with short pavement, although even with long pavement it cannot be entirely eliminated. 4 fstm?6-1976 b) Stmi-modular Out&s - Semi-modular outlets are the outlets whose discharge although depending on the water level in the distributing channel, is independent of the water level in the water course so long as the minimum working head required for their working is available. Modular Outlets - Modular outlets are the outlets whose discharge is independent of the water levels in the distributing channel and the water course, within reasonable working limits. This type of outlets are either with moving parts or without moving parts, In the latter case these are called as rigid modules. Modular outlets with moving parts are not simple to design These are liable to and construct and are, thus, expensive. derangements due to increase in friction, rusting of the moving parts and any obstruction in the working of moving parts caused by the silt and weeds carried in flowing water. 4 4. GENERAL REQUIREMRNTS FOR OUTLETS 4.1 An outlet shall be strong and shall not have moving parts liable to derangements or requiring periodic attention. 4.2 Interference by the cultivator must be difficult and, if made, shall be readily detectable. 4.3 The outlet shall draw its fair share of silt carried by the distributing channel, but shall not be liable to derangement by silt or weeds. 4.4 It shall be possible for the outlet to work efficiently with a small working head. 4.5 The cost of outlet shall not be high. 5. NON-MODULAR OUTLETS 5.1 Pipe Outlets - A pipe outlet with exit end of the pipe submerged in water in the water course works as a non-modular outlet. The pipes are placed horizontally and at right angles to the centre line of the distributing channel. Discharge through the pipe outlet is given by the formula: Q = CAq2gH where C = coefficient of discharge which depends on friction factor, length and size of the pipe outlet; = 1 2 x 10s J +J$;) 5 ; xst7986-lM6 f = coefficient of fluid friction for pipes. Its value would be 0'005 and 0`01 for clean and slightly encrusted iron pipes respectively. For earthenware pipes its value can be taken as 0'007 5; of pipe in metres; and of pipe in cm. fluid friction of outlet pipes shall be as L = length d = diameter 5.1.1The values of C for different given in Table 1. TABLE 1 COEFFICIENT OF DISCHARGE FOR DIFFERENT FLUID FRICTION LEIWTHOBTHE PIPE DIAMIDTEB OB PIPE COEXTI~IENT OF DISOHABQE, C ' f=O-005 (3) fSOiO1 (4) - (1) m (2) cm 10 3 :; 25 10 0.69 x10-' 0.725 x 10-d 0.745 x 10-4 0.758 x IO-' 0.653 x 0.68 x 0.707 x 0.725x 0687x OS41 x 0*674x 0.697 x lo-' lo-' lo-` 1CY lo-' lo-' IO-' lo-' 0.609 0.66 0.69 0.711 0.535 0.594 0.632 0.659 x lo-' x lo-` xlp x IO-' x x x x 10-a lo-' lo-' lo-' 5 :?I 25 10 7 :o" 25 10 0.482 x IO-' x'54;; ;; -4 . @618X lo-' 0.443 x lo-4 0506x 10-r 0.55 x10-4 0*583x 10-r 9 :i 25 10 15 zs 10 15 :i 0.55 x lo-' 0.609 x lo-` . g;:; ;g 12 0:506x lo-' Of167 x IO-' 15 @472x 0.535 x 0.577 x 0%09x 10-r lo-' 10-L IO-' . 6 lS:7986-l!976 5.1.2 The discharges for different heads are listed in Table 2. TABLE 2 DISCHARGES FOR DIFFERENT HEADS COEIWICIENT OB FRICTIONS = 0.01 ~__ LENQTH OF THE PIPE ZIIAM~EB OB PIPES cm 0.20 m DISCHARGE q IN CUMECS x 10-4 for H - ___ o-30 m 0.40 m 0.50 m 0.75 m 1.0 m 4 8 0 0 o-021 2 0.0516 O-096 0 0.154 4 0.018 0.046 0.087 0.143 6 5 9 3 m -3 10 15 z 10 15 z 10 15 i"5 10 9 :s 25 10 12 :: 25 10 15 0.009 5 0'023 1 oa3 0 O-069 0 0.008 0.020 0.039 0.064 0.007 0,019 0.036 0.060 0,006 0.017 0.034 0.056 0.006 0.016 0.031 0.052 0.005 o-014 0.029 o-049 3 8 4 1 4; 1 5 1 8t 7 2 7 1; 1 5 6 6t 9 4 2 O-011 6 0.028 3 O-052 5 O-084 4 O*OlO2 0.025 5 0.048 0 0'078 3 o-009 0.023 0.044 0.073 lf 4 6 4 0.013 0.032 0.060 0.097 4 7 7 7 0.015 0.036 0.067 0'109 0 5 9 2 _ 0.018 0.044 0.083 0.134 5 O-0118 0.029 4 0'055 6 O-090 6 0'010 6 O-027 0 0.051 6 0.084 9 0.009 74 L 0.025 0 0'048 3 O-080 2 O-008 0.022 0.044 o-074 7tj 8 5 4 O-013 2 0,032 9 0.062 0 0'1013 0'011 0.030 0.057 0.095 9 2 6 0 0.016 0 0.040 2 0.076 0 O-123 9 0.014 5 0.037 1 0.070 6 O-1162 0.013 4 0.034 3 O-062 3 O-109 6 0.012 0.031 0'060 0'101 0 3 9 7 7 0.016 8 0.042 6 fs 5 O-008 4: 0.021 7 O-04 1 8 O-069 3 0.007 0.019 0.038 0.064 5t 8 5 4 0'010 9 0'028 0 0.054 1 O-089 6 0'009 @025 0'049 0.083 0.009 0.023 0.046 0.077 8 5 7 2 0 5 4 8 0'015 4 0.039 6 O-076 4 0.126 8 0.013 9 O-036 0 0.070 4 0.117 7 0'012 o-033 0.065 o-110 7 3 7 1 15 0.006 91 O-018 2 0.035 9 O-060 1 0.008 01 x:00:: s 0'0696 : 00110 0.028 8 0.056 8 0.095 0 5.2 It is a common practice to place the pipe at the bed of the distributing The inlet channel to enable the outlets to draw fair share of silt charge. and exit ends of pipe should be preferably fixed in masonry to prevent Typical layout of this class of outlet is shown in Fig. 1. tampering. 5.3 Pipe outlets are adopted in the initial stage of distribution or for additional irrigation in a season when spare supply is available. 7 IS : 7986 - 1976 PLAN SECTION 22 SECTION XX NOTE-Where of the pipe outlet. necessary suitable pitching may be provided at the down-stream FIG. 1 PIPE OUTLET 5.4 The discharge in this class ofoutlets can be increased by deepening the water course and thereby lowering the water surface level in it. The discharge varies from outlet to outlet because of flow conditions and also at different time on the same outlet due to silt charge in the distributing channel. 5.5 These are serious drawbacks in this class of outlets. 6. SEMI-MODULAR OUTLETS 6.1 Pipe OutIets - The pipe outlets described in 5.1 work as semi-modules when the discharge has free fall into the water course. This class of outlets may therefore be used as semi-modular outlets in which case the exit end of pipe is placed higher than the water 1eveI in the water course. In this case working head H is the difference between water level in distributing channel and centre of pipe outlet. 6.2 Open Flume Outlets - The open flume outIet is simpIy a smooth weir with a throat constricted sufficiently to ensure velocity above critical and long enough to ensure that the controlling section remains within the paraIle1 throat at a11 dischgrges up to the maximum. A gradually expanded flume is provided at the outfall to obtain the maximum recovery of head. The entire work is built in brick masonry but the controlling section is generally provided with cast iron or steel bed and check plates (see Fig. 2 and Fig. 3 ). 8 f z s E 3 Li a -----P-e______ -----.m--_____ WIDTH OF PARAPET IS KEPT TO SUIT WE SIZE OF AOJUSTABLE PROPORTIONAL HOOULE i /f 1 71 -+ -- 1 I I -- 90 -I 44 - it Tx I_-I __ -I 1 go z / r?OP SHOULD BE Ik LEVEL WITH UPSTREAM WALL , ? 1 SECTION XX bed width of distributary reduced below outlet downstream wing wall should be at downstream toe of slope and upstream wing at upstream toe of slope *Where iWhere bed of water course is lower than floor of outlet downstream curtain and wing walls to be taken down 30 cm below bed of water course and if necessary a cistern to be provided All dimensions in centimetres. FIG. 3 TYPE PLAN OF OPEN FLUME OUTLET WITH ROOF BLOCK IS : 7986 - l.976 6.3 Cramp's Adjustable Proportional Module ( Crump's A. P. M. ) This type is the most commonly used outlet under this class. In this type of outlet, C. I. base, C. I. roof block and check plates on either side The roof block is fixed form the nucleus around which masonry is built. to the check plates by bolts which can be removed and depth of the outlet adjusted after the masonry is dismantled. This type of outlet cannot be easrly tampered with and at the same time can be conveniently adjusted at a very small cost. Typical layout of this type of outlet is shown in Fig. 4. W' - k $ ( B, + D/2 ) Q ( cumecs ) Below 0'283 Over 0'283 and up to 1.415 Over 1'4 15 and up to 5'660 Over 5'660 k 1'00 1'25 1'50 2'00 6.3.1 The discharge in this type of outlet is given by the formula: q = 4'03 B, 2a) Ratio 7 K should be between distribution of silt b) Ratio -2 should be 0'8 or less for modular working 2/z 0.375 to 0'48 for proportionate 6.3.2 The base plates and the roof blocks are manufactured in standard srzes, such axBt =- 6'1, 7'6, 9'9, 12.2, 15'4, 19.5, 24'4 and 30.5 centimetres. These standard sizes with required opening of the orifice are used to obtain desired supply through the outlet. 6.4 The waterway in this type of outlets is either deep and narrow which could get blocked easily or is shallow and wide in which case it does not draw its fair share of silt. 11 IS t 7986 - 1976 ROD DETAILS OF ROOF BLOCK IDTH NAL J--dPLAN LONGITUDINAL SECTION All dimensions in centimetres. F1c.4 CRUMP'SADJUSTABLE PROPORTIONAL MODULE 12 BUREAU OF INDIAN STANDARDS Headquarters : Manak Bhavan, 9 Bahadur Shah Zafar Marg, NEW DELHI 110002 Telegrams : Manaksanstha Telephones : 3 31 01 31,3 31 13 75 ( Common to all Offices ) Telephonb Regional Offices : *Western tEastern Northern Southern ; Manakalaya, BOMBAY E9 MIDC, Marol, Andheri 400093 ( East ), 6 32 92 85 36 24 99 2 18 43 { 31641 (41 24 42 4 41 25 79 141 2916 2 63 48 { 2 63 49 22 48 05 6 27 16 5 36 27 22 10 83 6 { 6 21 (. 21 6 34 98 68 82 23 52 71 32 76 92 05 27 : l/l4 C. I. T. Scheme VII M, V. I. P. Road, Maniktola, CALCUTTA 700054 Sector 35-C 160036 : SC0 445-446. CHANDIGARH : C. I. T. Campus, MADRAS 600113 Branch Offices : Pushpak,' Nurmohamed Shaikh Marg, Khanpur, AHMADABAD 380001 `F' Block, Unfty Bldg, Narasimharaja Square, BANGALORE 560002 Gangotri Complex, 5th Floor, Bhadbhada Road, T. T. Nagar, BHOPAL 462003 Plot No. 82/83, Lewis Road, BHUBANESHWAR 751002 5315 Ward No. 29, R. G. Barua Road, 5th Byelane, GUWAHATI 781003 5-8-56C L. N. Gupta Marg. (Nampally Station Road), HYDERABAD 500001 R14 Yudhister Marg. C Scheme, JAIPUR 302005 117/418B Sarvodaya Nagar. KANPUR 208005 Patliputra lndustriaf Estate, PATNA 800013 Hantex Bldg ( 2nd Floor ), Rly Station Road,. TRIVANDRUM 695001 lnspectim Office ( W*ith S&e PO@): Institution of EngincPers ( IBdia).Bfritding, PUNE 4y0005 1332 Shivaji Nagar, 5 24 35 89 85 28 27 88 00 *Sales Office in Bombay is at Novelty Chambera. Grant Road, Bombay 400007 j tSales Office in Calcutta is at 5 Chowringhse Approach, P. 0. Princrp Street, Calcutta 700012 Reprography Unit, BIS, New Delhi, India AMENDMENT NO. 1 JANUARY 1992 TO IS 7986 : 1976 CODE OF PRACTICE FOR CANAL OUTLETS (Puge 11, clause63.1, line2 ) -Substitute `di%' /or `d? . (RVD13) Reprography Unit, BIS, New Delhi, India